Hello Mighty,
Q. Does the body use diseased protein before fat as a fuel source?
AND.... will the body only use diseased tissue for the little bit of protein the body needs to convert to glucose to feed the brain?
In answer to those questions, the Brain will only feed on minimal amounts of glucose during a fast, as its main fuel sources are ketone bodies (beta-hydroxybutyrate and acetoacetate)....................
http://www.ncbi.nlm.nih.gov/pubmed/6061736
Due to the lack of incoming energy, the body must turn to its own resources, a function called autolysis.
http://www.soilandhealth.org/02/0201hyglibcat/020127shelton.III/020127.ch5.htm
"It will be observed that during the fast the tissues do not all waste at an equal rate; those that are not essential are utilized MOST rapidly, those LEAST essential less rapidly and those MOST essential not at all at first and only slowly at the last. Nature always favors the most vital organs. The fat disappears first, and then the other tissues in the inverse order of their usefulness. The essential tissues obtain their nourishment from the less essential, by enzymatic action, a process which has been termed autolysis".
http://www.soilandhealth.org/02/0201hyglibcat/020127shelton.III/020127.ch7.htm
"Just as fasting causes the body to consume its excess of fat and use this to nourish its vital tissues, so it causes the body to break down, by autolysis, growths, or tumors and use the nutritive substances in these to nourish its vital tissues. In like manner dropsical swellings, edematous swellings, and deposits are absorbed and the usable portions salvaged for use in nourishing the vital tissues".
http://www.soilandhealth.org/02/0201hyglibcat/020127shelton.III/020127.ch21.htm
"Fasting, because it compels the body to rely upon its internal resources, forces the tearing down (by autolysis) of growths, effusions, infiltrations, deposits, accumulations and excesses. These are thoroughly overhauled, their usable constituents are employed in nourishing the vital tissues, their unusable portions are excreted".
http://www.soilandhealth.org/02/0201hyglibcat/020127shelton.III/020127.ch22.htm
Autolysis is basically the breaking down of effluent materials while simultaneously feeding from fat stores in the body in order to produce energy, and in the least order of tissue-importance first.
It is a very discerning process, which will only allow the body to utilize unwanted and unnecessary materials first and foremost, and that includes waste products of metabolism and other effluent materials sourced externally, BEFORE and WHILE burning fat via ketosis as the main fuel source.
It is the liver which is in charge of converting the fats into a chemical called a ketone body, "the metabolic substances acetoacetic acid and beta-hydroxybutyric acid", and then distributing these bodies throughout the body via the blood stream.
When this fat utilization occurs, free fatty acids are released into the blood stream and are used by the liver for energy. The less one eats, the more the body turns to these stored fats and creates these ketone bodies, the accumulation of which is referred to as ketosis.
The link you have Mighty is Sheltons book: "Natural Hygiene, Mans Pristine Way of Life" which although very good in itself, is not the main source of information regarding fasting found here...........
http://www.soilandhealth.org/02/0201hyglibcat/020127shelton.III/020127.toc.htm
AND HERE.........
http://chestofbooks.com/health/natural-cure/The-Hygienic-System-Fasting-and-S...
AND HERE.........
http://www.rawfoodexplained.com/introduction-to-fasting/
Protein as a fuel source is minimized by the body in what Fuhrman describes as "protein-sparing": a conservation measure by the body in preserving its protein/muscle-stores via AUTOLYSIS.
Hope this has been of some help.
Chrisb1.